Named for Rustler Canyon in northwest part of quad., Grant Co., NM in the Basin-and-Range province. Mapped (geologic map) on west side of Box Canyon, secs. 6 and 7, T 19 S, R 10 W as a very thin unit between the older Box Canyon rhyolite (first used) and the younger informally named Piloncillo sediments. Maximum thickness is 50 ft. The basalt is black, vesicular, and finely crystalline; it contains sparse flakes of iddingsite; some vesicles are filled with opaline silica. Also mapped in secs. 20 and 21, T 18 S, R 11 W. Rustler Canyon consists of vesicular and amygdaloidal flows, flow breccias, and minor sandy tuffs lying between the Kneeling Nun tuff and the Caballo Blanco rhyolite (named). Thought to be more widespread south of Santa Rita, NM. Tertiary age assigned. Is part of the "Lower volcanic series."

Source: GNU records (USGS DDS-6; Denver GNULEX).